Seals for boilers

ABSTRACT

This application covers a boiler having adjacent outer wall sections which have grooves or channels at the interfaces or lands of the adjacent sections, into which are inserted a fibrous rope material, such as asbestos rope, impregnated with and surrounded by a pliable elastic sealant, such as silicone rubber, filling the grooves or channels, thereby rendering the wall sections leak-proof for the flue gases at all ambient temperatures encountered in the operation of the boiler and at all flue pressures, including super-atmospheric flue pressures encountered in forced draft boilers.

States Patent 11 1 [111 3,839,993 Peterson Oct. 8, 1974 SEALS FORBOILERS [75] Inventor: Edgar M. Peterson, Fanwood, NJ. Pmfwry Examlf'er'carron D or I Assistant Exammer-Larry I. Schwartz [73] AssigneezAmerican Standard Inc., New York, A t A or Firm-R b rt G, C ok JeffersonEhrlich; James J. Salerno, Jr. [22] Filed: Mar. 9, 1973 211 Appl. No.:339,809 [57] ABSTRACT 4 This application covers a boiler having ad acentouter wall sections which have grooves or channels at the if g 122/122031 277/229 interfaces or lands of the adjacent sections, into which[581 Fltt. F1221) 23/04. are inserted a fibrous rope material, Such asasbestos 1 IBM or earch 122/225, 231, 126/190, rope impregnated i andSurrounded by a pliable 277/229 elastic sealant, such as siliconerubber, filling the grooves or channels, thereby rendering the wall sec-[56] References C'ted tions leak-proof for the flue gases at all ambienttem- UNITED STATES PATENTS peratures encountered in the operation of theboiler 1,516,130 11/1924 Wirfs 126/190 X and at all flue pressures,including super-atmospheric 3,261,328 7/1966 Mueller 122/225 R fluepressures encountered in forced draft boilers. 3,533,379 lO/l970 Martinet al.... l22/23l 3,729,205 4/1973 Kwok 277/229 6 Claims, 7 DrawingFlgures OUTSIDE OF BOILER INSIDE OF BOILER PATENTEDUCI 81974 3.839.993SUE" 1 of 3 FI.G.|-

ISI AR GV |s2 AR GR PAIENIEU BT 81914 I SHEET 2 0F 3 F I G 2 OUTSIDE OFBOILER INSIDE O BOILER F l G 4 SEALS FOR BOILERS This invention relatesto boilers and, more particularly, to boilers which are to be operatedunder forced draft and sealed against super-atmospheric pressures andtemperatures encountered in operation.

Forced draft boilers of the sectional type are often preferred againstconventional boilers operating at normal pressures for furnishing heatrequired by large commercial installations and even by small homes. Itis an acknowledged fact that a forced draft boiler advantageouslyrequires very little, if any, draft-creating chimney or ventingpassages, i.e., passages extending above the rooftop of the building inwhich the boiler may be installed. Forced draft sectional boilers may beuseful with vents or chimneys no more than about 3 feet high and ofttimes without any protruding upwardly extending passages reaching out ofa building.

However, the installation and use of forced draft boilers haveheretofore been resisted by architects because there may be real hazardin the leakage of obnoxious or lethal gases which may be dissipatedthrough crevices however small, especially through openings at theadjacent interfaces or lands at which the sections of the boiler aremated for confining the generated gases. Such reactions have, at times,affected potential sales of such boilers and cost-savings to users ofthem.

Asbestos rope has heretofore found acceptance for insertion into theadjacent grooves or channels at the mating ends of the sections, butsuch structures have not been approved, and should not be approved, foruse in boilers operating under forced draft. Such boilers havingasbestos rope construction are shown and described, for example, in theJ. C. Mueller US. Pat. No. 2,935,052, filed May 3, 1960; US. Pat. No.3,215,125, issued Nov. 2, 1965; and US. Pat. No. 3,261,328, issued July19, 1966. It is acknowledged that asbestos rope is especiallyundesirable for sealing forced draft boiler construction unless suitablytall chimneys or other exvacuators of the gaseous fumes are employed.This is principally because asbestos rope is porous and embodiesnumerous void spaces and therefore is not, and cannot be, impervious tothe flue gases developed in the firebox, especially at superatmosphericpressures. Furthermore, such asbestos rope is usually driven into thegrooves or channels of the mating adjacent wall sections so as to extendbeyond the edges of the grooves or channels and hence, when the sectionsare drawn together, the segments of the asbestos rope extending beyondthe grooves or channels may well provide avenues for the escape of thepressurized gases. Even when the asbestos rope is confined within thespaces provided by the grooves or channels, similar escape routes willbe provided through the spaces however small between the outer surfaceof the rope and the inner wall of the grooves or channels, again therebyproviding free exit for the developed pressurized gases. Therefore,notwithstanding the desirably qualities of asbestos rope structures,they are unsuitable for sealing boilers developing pressurized gaseousfumes.

According to the present invention, a rope material, such asconventional asbestos rope, has been specially developed for pressurizedgases of boilers. The rope material developed should be fully coatedwith a pliable and elastic material, which is leak-proof at all ambienttemperatures and fluid pressures encountered in forced draft boilersystems. The material should remain pliable and elastic material evenafter it is applied and even when it is subjected to gaseous pressure.The composite material should effectively seal the void spaces withinthe rope material and also the spaces between the rope material and theinner walls of the grooves or channels in the mating faces of adjacentsection walls of a boiler so to render the joined section wallsleakproof and safe at all times even for use in homes. The elasticsealant material preferably should have the consistency of a toothpasteand yet be easily and rapidly applicable to the rope material. Suchelastic sealant may be conveniently applied, for example, by aconventional hand-caulking gun. The elastic sealant may be applied tothe rope and, furthermore, the ropetreating process may be applied evenat the site where the boiler sections are to be assembled and thefinished boiler mounted for use.

One of the principal objects of this invention, therefore, is to providea grooved joint at the mating lands or interfaces of adjacent sectionsof a multi-section boiler, the joint comprising a combination ofmaterials composed of a form of stranded rope together with asuperimposed elastic sealant supplied to fill the groove to preventleakage of gas through or around the joint.

Another of the objects of this invention is to provide a permanentsealant arrangement within the grooves or channels at the interfaces orlands of adjacent sections of a boiler, the grooves or channels beingfilled with a fibrous material impregnated with a pliable elastomer torender the boiler impervious to gases and leak-proof even atsuper-atmospheric pressures and invulnerable to radiant heat generatedwithin the boiler.

These and other objects of this invention, as well as its features andadvantages, will be better and more clearly understood from thefollowing more detailed description and explanation hereinafterfollowing when read in connection with the accompanying drawing inwhich:

FIG. 1 schematically illustrates a cross-sectional view taken along acenterline perpendicular to the front of a boiler incorporating theinvention;

FIG. 2 illustrates a simplified sketch, in amplified form, of one formof structure insertable into the grooving or channeling for sealingadjacent mating sections of a boiler according to this invention;

FIGS. 3, 4, 5 and 6 schematically illustrate other modifications of thechanneling or grooving of adjacent boiler sections for practicing thisinvention; and

FIG. 7 schematically illustrates a front elevational view of the innerside of a single section of a boiler arranged according to thisinvention, the figure showing generally the application of the inventionto the internal wall surface.

The same or similar reference characters will be employed throughout thedrawing to designate and illustrate the same or similar parts whereverthey may occur throughout the drawing.

Referring to the drawing, FIG. 1 illustrates only the importantapparatus or components of a boiler required to explain the invention.FIG. 1 shows, in schematic form, a four-section cast iron boilersuitable for operation not only at normal pressures, but also atsuper-atmospheric pressures. The construction of FIG. 1 includes thefront section FS of the boiler, the rear section RS and two intermediatesections 181 and [S2, all of which are adjacent to each other as shown.The illustrative embodiment includes a burner unit (not shown) whichwould be adjacent to, or partly within, the lower left-hand corner ofthe boiler, as illustrated in FIG. 1, and which would be mounted andoperated in the customary way to supply a flame for igniting, on acontinuing basis, gas which is supplied to the burner, together withmeans to introduce pressurized air to aid and accompany the flame. Thegas will be ignited in the firebox FB and, under the influence of thepressurized air, radiant heat will be generated and channeled betweenthe several sections somewhat along the direction lines shown in FIG. 1to the smoke chamber SC leading to the exhaust vent EX. The burner unitmay be of any type such as, for example, described in a patent of A. E.Martin, US Pat. No. 3,406,002, issued Oct. 15, 1968, entitled Cup ConeFlame Retention Burner," assigned to the assignee of the presentapplication. The burner unit is preferably designed to operate on fluidfuel and to generate heated gas at a pressure within the firebox FBwhich is above atmospheric pressure. The pressure of the flue gaseswithin the firebox FB may be, for example, 0.2 or 0.5 inches of water,and it may be as high as, or substantially much higher than 3 inches ofwater. However, it is a sufficient pressure to readily overcome thenormal resistances encountered by the flue gases in traveling throughthe several non-linear passages shown by the direction lines of FIG. 1.Notwithstanding the operation of the boiler at superatmosphericpressures, the customary chimney or venting passages, which are externalto the boiler and usually extend to or above the rooftop of the buildingin which the boiler is installed, may be unnecessary and may bedispensed with and instead a much shorter passage, such as a 3 foot highvent or chimney EX, for example, may be sufflcient for most, if not all,contemplated installations, whether for a commercial building or for aone-family or multi-family home.

It will be observed from FIG. 1 that a groove or channel, or a pluralityof grooves or channels, are provided at the mating or land segments ofadjacent cast iron channels. FIG. 2 illustrates, in amplified form, aview of the two adjacent cast iron channels I81 and IS2 which areleaklessly coupled to each other, according to the invention.

The mating surfaces of FIG. 2 illustrate a substantially V-shaped grooveGV formed in one of the channels IS2 in which is inserted an asbestosrope AR encased in a pliable elastic sealant SE so as to completely fillthe lengthy longitudinal V-shaped groove GV. The flue gases, which maybe at super-atmospheric pressure, impinge against the inner walls ofsections 181 and [S2 but are incapable of leaking through the protectivebarrier provided by the combination of the rope AR and seal SE withingroove GV. By viture of the full closure at the inner wall of the twoadjacentsections I81 and [S2, the radiant heat generated within theboiler is incapable of attacking nd deteriorating or otherwise adverselyaffecting the sealant SE as well as the enveloped rope AR even attemperatures exceeding 500F. The composite joint is, therefore, fullyprotected against the high temperatures and the destructive effect ofthe radiation generated by the flue gases.

FIG. 3 shows two adjacent sections, marked [S3, of a multi-sectionboiler in which two triangular grooves, both designated GV3, areprovided, one in each of the respective sections 153, as shown. Asimilar fibrous rope of, for example, asbestos and designated AR3 isinserted into the ajacent longitudinal V-shaped grooves, and the sealantSE3 is inserted into both grooves GV3 to fill the spaces within the ropeAR3 and the spaces exterior to the surfaces of the rope AR3. The sealantSE3 so inserted into the interstices of the rope AR3 renders the ropesubstantially leak-proof against the generated flue gases. The sealantSE3 also applied to the spaces about the rope AR3 within the two groovesGV3 of both sections 153, as shown, renders these spaces leakproofagainst the flue gases. The inner lands of the mating sections arevirtually closed against access by the gases for the further protectionof the lengthy longitudinal joint. It will be apparent from the shape ofthe outer lands of the FIG. 3 arrangement that the sealant SE3 may beapplied from a handcaulking gun. This makes possible and practical theassembly of the wall sections of the boiler on the location where thesections are to be installed and used.

FIG. 4 shows two wall sections, both designated I54 and each having asemi-cylindrical longitudinal groove GV4 within which is inserted asimilar fire-proof rope AR4 surrounded by a sealant SE4 to render thecombination joint impregnable and impervious against the flue gases evenat super-atmospheric pressures.

FIG. 5 is another variation of the companion wall sections 185, each ofwhich is channeled by semicylindrical grooves GV5 of ellipticalcross-section. Asbestos rope ARS, or a like medium, is inserted into theelliptical cross-section and the exterior of the rope ARS encased inpliable elastic sealant SE5. The upper outer portions of the matingwalls are provided with suffrciently wide spaces, as shown, to enablethe sealant to be applied from the exterior of the wall structures and,if desired, at the place where the boiler installation is to be made.The rope ARS may have a diameter which is less than the minor axis ofthe cylindrical cavity of elliptical cross-section so that, when theconventional rods of the boiler are drawn up to tighten the wallsections, the rope ARS may be subjected to mechanical pressure to holdthe rope ARS firmly in place. The sealant SE5 may be applied to the ropeAR5 and to the grooves GVS either before the wall assembly or after thewall assembly, as may be desired. An excess of the sealant SE5 will notadversely affect the protective ability of the joint.

FIG. 6 shows the mating walls of two adjacen cast iron sections [86arranged so that but one of the mating walls is grooved to have asemi-cylindrical contour of semi-circular crosssection and of sufficientdimensions so as to conveniently receive the rope AR6. The sealant SE6not only surrounds the rope AR6 but also fills the internal spaces ofthe rope AR6 so that the groove GV6 is completely filled and may befilled to over-flowing, as already suggested supra. The sealant SE6 alsomay be applied from an exterior position after assembly of the sectionsbecause of the spacing on the upper-outer portions of the mating wallsof the adjacent sections IS6.

FIG. 7 illustrates schematically one form of the inner wall of a sectionIS7 of a super-atmospheric boiler according to this invention. It willbe observed that the groove GV7 extends, or may extend, around theentire periphery of the internal wall of the section 187. Within thegroove GV7 will be inserted the rope AR7 and the sealant SE7 in order tocompletely fill the groove GV7, as already observed supra.

The fibrous rope above referred to is preferably formed of asbestos andselected for its well-known fireproof qualities which resist destructioneven at much higher temperatures than are normally developed insuper-atmospheric boilers. The rope may have, for example, a diameter ofabout /2 inch. Such a rope may, and ordinarily is, formed of a group ofstrands, perhaps four in number, which are braided and twisted inserpentine fashion along a longitudinal axis. As is well known, each ofthe strands is capable of being unravelled and is stretchable. Thecomponents of each strand, and of the strands that are joined together,easily fall apart. Such a flimsy structure is, per se, highly unsuitableas a sealant for gases under any applied gaseous pressure however small.The interstices of the fibers and of the overall rope in general areopen avenues for the free release of any and all gases that reach therope.

According to the present invention, the asbestos rope above referred tois made useful and practical as a sealant under pressurized flue gasesmerely by coating the rope and filling, partially of completely, theinterstices of its fibers and filling the spaces ajdacent the outerperiphery of the rope. A sealant which is pliable and elastic and has asilicone rubber base not alone serves to render the rope impervious topressurized gases but, equally importantly, binds the fibers and theirstrands together so that they are unified and encased and remain unifiedand encased thereafter.

The draw rods for drawing the sections of the boiler together have notbeen shown to avoid needless complication in the drawing. However, theyare customarily employed to hold the sections in place and, in thepresent case, they serve to maintain the treated internal wall formed bythe sections continuously leak-proof.

A flexible rope impregnated with a silicone rubber of the type involvedin this invention will resist destruction by high gas temperatures and,even should some part of the external sealant for the rope becomesweakened, the combination of the rope and the remainder of the activesilicone material within the groove will be shielded and will maintainprotection for a long time.

One form of sealant, entirely satisfactory for use in the presentinvention, is known as Silastic and it is made by Dow-Coming Corporationand sold as Silastic 732RTV Silicone Rubber. A similar product is madeby other manufacturers. Such material is easily applied by hand orthrough a caulking gun. Smaller boilers may be built and sealed at thefactory, but very large boilers can easily be installed and sealed atthe site of use without difficulty.

While this invention has been shown and described in certain particularembodiments for illustration, it will be understood that the featuresand objectives of this invention are readily applicable in many andvaried forms.

What is claimed is:

l. A boiler having two exteriorly arranged wall sections with closelyadjoining mating sides facing the flue gas produced within the boilerand having a groove at the interface filled with a gas impervioussealing means to prevent the leakage of flue gas therethrough,

said sealing means comprising:

a fibrous flexible asbestos rope, and

a coating of a pliable silicone sealant of the type that is resistant todeterioration at temperatures exceeding 500F. and which partiallypenetrates the outer surfaces of the rope to at least fill and seal thevoids and interstices at the periphery of the rope to provide a sealingmeans which is impervious to the gases generated within the boiler andresistant to destruction by said high flue gas temperatures even wherepartial destruction of the sealant occurs at the flue gas side of theboiler section.

2. A forced draft boiler having a plurality of mating wall sectionsarranged and constructed to form at least one of the exterior walls ofthe boiler,

each pair of wall sections having a groove at the interface thereof,

sealing means positioned in said groove between said sections to providea leakproof seal against flue gases under super-atmospheric pressures,

said sealing means comprising:

a fibrous flexible asbestos rope formed to fill a large part of saidgroove, and

a coating of pliable silicone sealant of the type that is resistant todeterioration at temperatures exceeding 500F. and which partiallypenetrates the outer surfaces of the rope to at least fill and seal thevoids and interstices at the periphery of the rope to provide a sealantmeans which is impervious to the gases generated within the boiler andresistant to destruction by said high flue gas temperatures even wherepartial destruction of the sealant occurs at the flue gas side of theboiler section.

3. A boiler for operation at atmospheric and superatmospheric flue gaspressures comprising:

at least two adjacent wall sections,

said adjacent wall sections having a groove formed at their interfaceand sealing means positioned in said groove to provide a leakproof sealagainst said flue gases,

said sealing means comprising:

a fibrous flexible asbestos rope formed to fill a large part of saidgroove, and

a coating of a pliable silicone sealant of the type that is resistant todeterioration at temperatures exceeding 500F. and which partiallypenetrates the outer surfaces of the rope to at least fill and seal thevoids and interstices at the periphery of the rope to provide a sealingmeans which is impervious to the gases generated within the boiler andresistant to destruction by said high flue gas temperatures even wherepartial destruction of the sealant occurs at the flue gas inside of theboiler section.

4. A forced draft boiler according to claim 3 in which the fibrous ropeis formed into strands which are twisted in serpentine fashion abouteach to form a substantially cylindrical contour.

5. The combination of two adjoining longitudinal plates having similarlymated end walls,

and having retaining means adapted to receive sealing means between twoadjoining longitudinal plates to provide a leakproof seal against fluegases,

said sealing means positioned in said retaining means and capable ofmaintinaing a seal at superatmospheric pressures extending above 3inches of of the rope to provide a sealing means which is impervious tothe gases generated within the boiler and resistant to destruction bysaid high flue gas temperatures even where partial destruction of thesealant occurs at the flue gas side of the boiler section. 6. Thecombination of claim 5 in which the plates are made of ferrous materialand the fibrous rope is made of asbestos material.

1. A boiler having two exteriorly arranged wall sections with closelyadjoining mating sides facing the flue gas produced within the boilerand having a groove at the interface filled with a gas impervioussealing means to prevent the leakage of flue gas therethrough, saidsealing means comprising: a fibrous flexible asbestos rope, and acoating of a pliable silicone sealant of the type that is resistant todeterioration at temperatures exceeding 500*F. and which partiallypenetrates the outer surfaces of the rope to at least fill and seal thevoids and interstices at the periphery of the rope to provide a sealingmeans which is impervious to the gases generated within the boiler andresistant to destruction by said high flue gas temperatures even wherepartial destruction of the sealant occurs at the flue gas side of theboiler section.
 2. A forced draft boiler having a plurality of matingwall sections arranged and constructed to form at least one of theexterior walls of the boiler, each pair of wall sections having a grooveat the interface thereof, sealing means positioned in said groovebetween said sections to provide a leakproof seal against flue gasesunder super-atmospheric pressures, said sealing means comprising: afibrous flexible asbestos rope formed to fill a large part of saidgroove, and a coating of pliable silicone sealant of the type that isresistant to deterioration at temperatures exceeding 500*F. and whichpartially penetrates the outer surfaces of the rope to at least fill andseal the voids and interstices at the periphery of the rope to provide asealant means whiCh is impervious to the gases generated within theboiler and resistant to destruction by said high flue gas temperatureseven where partial destruction of the sealant occurs at the flue gasside of the boiler section.
 3. A boiler for operation at atmospheric andsuper-atmospheric flue gas pressures comprising: at least two adjacentwall sections, said adjacent wall sections having a groove formed attheir interface and sealing means positioned in said groove to provide aleakproof seal against said flue gases, said sealing means comprising: afibrous flexible asbestos rope formed to fill a large part of saidgroove, and a coating of a pliable silicone sealant of the type that isresistant to deterioration at temperatures exceeding 500*F. and whichpartially penetrates the outer surfaces of the rope to at least fill andseal the voids and interstices at the periphery of the rope to provide asealing means which is impervious to the gases generated within theboiler and resistant to destruction by said high flue gas temperatureseven where partial destruction of the sealant occurs at the flue gasinside of the boiler section.
 4. A forced draft boiler according toclaim 3 in which the fibrous rope is formed into strands which aretwisted in serpentine fashion about each to form a substantiallycylindrical contour.
 5. The combination of two adjoining longitudinalplates having similarly mated end walls, and having retaining meansadapted to receive sealing means between two adjoining longitudinalplates to provide a leakproof seal against flue gases, said sealingmeans positioned in said retaining means and capable of maintinaing aseal at super-atmospheric pressures extending above 3 inches of water,and when exposed to flue gases radiating heat at temperatures up to andabove 500*F. said sealing means comprising: a fibrous flexible asbestosrope formed to fill a large part of said groove, and a coating of apliable silicone sealant of the type that is resistant to deteriorationat temperatures exceeding 500*F, and which partially penetrates theouter surfaces of the rope to at least fill and seal the voids andinterstices at the periphery of the rope to provide a sealing meanswhich is impervious to the gases generated within the boiler andresistant to destruction by said high flue gas temperatures even wherepartial destruction of the sealant occurs at the flue gas side of theboiler section.
 6. The combination of claim 5 in which the plates aremade of ferrous material and the fibrous rope is made of asbestosmaterial.